1. Field of the Invention
This invention relates to an in-line filter. More particularly, it relates to an in-line filter which can be used with standard tubing connectors designed for tubing carrying gases used in the manufacture of semiconductors.
2. Description of the Related Art
Various gases are employed in the manufacture of semiconductors. Because particulate matter in the gases can introduce flaws into the semiconductors being manufactured, it is important that the gases be of extremely high cleanliness. Therefore, it is common to install in-line particulate filters along tubing lines for carrying these gases. An in-line filter refers to a filter which has a straight-line flow path (the inlet, the filter element, and the outlet of the filter being coaxial) and which is easily installed in a tubing line.
A conventional in-line filter for use with tubing lines includes a spool-shaped fitting having a tubular body with connections at opposite ends and a filter element welded to the inside of the fitting. In use, the spool-shaped fitting is placed between two sections of tubing which are to be joined, and the ends of the fitting are sealingly connected to the two halves of a standard tubing connector installed on the ends of the tubing sections.
An in-line filter of this type has a number of drawbacks. One is that it increases the length of the tubing line by the length of the spool-shaped fitting, so it may be difficult or impossible to retrofit an existing tubing line with such a filter. Furthermore, because a connection is formed at each end of the spool-shaped fitting, the number of connections in the tubing line is greater than in the absence of the in-line filter, so the number of possible sources of contamination or leakage increases.